The spine is a flexible column formed of a plurality of bones called vertebrae. The vertebrae are hollow and piled one upon the other, forming a strong hollow column for support of the cranium and trunk. The hollow core of the spine houses and protects the nerves of the spinal cord. The different vertebrae are connected to one another by means of articular processes and intervertebral, fibrocartilaginous bodies. Various spinal disorders may cause the spine to become misaligned, curved, and/or twisted or result in fractured and/or compressed vertebrae. It is often necessary to surgically correct these spinal disorders.
The spine includes seven cervical (neck) vertebrae, twelve thoracic (chest) vertebrae, five lumbar (lower back) vertebrae, and the fused vertebrae in the sacrum and coccyx that help to form the hip region. While the shapes of individual vertebrae differ among these regions, each is essentially a short hollow shaft containing the bundle of nerves known as the spinal cord. Individual nerves, such as those carrying messages to the arms or legs, enter and exit the spinal cord through gaps between vertebrae.
Patients suffering from orthopedic injuries, deformities, or degenerative diseases often require surgery to stabilize an internal structure, promote healing, and/or relieve pain. In the spinal field, surgeries to correct spinal abnormalities often involve inserting spinal implants such as interbody spacers or cages between adjacent vertebrae to maintain the correct spacing and curvature of the vertebrae. Once the spinal implant has been inserted and maneuvered into proper place, stabilization elements such as screws and rods and/or plates or other types of stabilization elements may be used to secure the spinal implant and vertebrae for proper fusion.
Typically, a lumbar fusion procedure involves insertion of one or more intervertebral spacers through a posterior or transforaminal approach. Posterior lumbar interbody fusion (PLIF) and transforaminal lumbar interbody fusion (TLIF) are fairly common procedures that utilize inserter instruments. For example, U.S. Pat. No. 5,741,253 describes such an inserter. The inserters typically have a coupling feature for coupling with the spinal implant and in some cases, alignment or anti-torque features to prevent rotation of the spinal implant relative to the inserter once coupled with the inserter. The coupling feature may include a threaded fitting that extends into an opening or aperture of the spinal implant. The threaded fitting may be threaded into the opening to secure the spinal implant to the inserter. Additional attachment features may complement features on the spinal implant.